An Anopheles gambiae mosquito, which transmits malaria in the Ethiopian highlands. Image credit: Dan Salaman, London School of Hygiene & Tropical Medicine.

Researchers have debated for more than two decades the likely impacts, if any, of global warming on the worldwide incidence of malaria, a mosquito-borne disease that infects more than 300 million people each year.

Now, University of Michigan ecologists and their colleagues are reporting the first hard evidence that malaria does – as had long been predicted – creep to higher elevations during warmer years and back down to lower altitudes when temperatures cool.

The study, based on an analysis of records from highland regions of Ethiopia and Colombia, suggests that future climate warming will result in a significant increase in malaria cases in densely populated regions of Africa and South America, unless disease monitoring and control efforts are boosted and sustained.

"We saw an upward expansion of malaria cases to higher altitudes in warmer years, which is a clear signal of a response by highland malaria to changes in climate," said U-M theoretical ecologist Mercedes Pascual, senior author of a paper published online in Science March 6, 2014.

U-M EEB doctoral student Mauricio Santos-Vega is a coauthor along with their international collaborators.

The research is receiving widespread international media coverage, including in Time, Times of India, Newsweek, BBC, Reuters (The Chicago Tribune), Smithsonian, and the Weather Channel (including a video), and many Hindi and Spanish language media outlets.